Why only hot air rises and not cool air ?
Kindly refer to the link given below to get your answer :
https://www.meritnation.com/ask-answer/question/why-hot-air-rises-up/winds-storms-and-cyclones/492045
https://www.meritnation.com/ask-answer/question/why-hot-air-rises-up/winds-storms-and-cyclones/492045